Bombogenesis (Photo Credit: NASA)

The term “bombogenesis” (also referred to as “bomb cyclone”) is a term that many people outside of the meteorology community have seldom heard. The most common time that it will be used is typically during strong Nor’easter events, which are storms that have a strong northeasterly flow that bring large amounts of snow, rain, and damaging wind up the eastern coast. Bombogenesis does not occur very often, but when it does, it’s nerve wracking to forecast for due to the potential damage it can cause. So what is it?

In order to explain what this phenomenon is, there is a need to explain what a mid-latitude cyclone is first. A mid-latitude cyclone is a low pressure system that has a counterclockwise flow (“cyclonic”) in the middle latitudes. They typically form along a polar front and will have a warm front on the eastern side with a cold front on the western side. These typically occur during the cooler months of the year between October and March. With that being said, bombogenesis is when a mid-latitude cyclone drops 24 or more millibars in surface barometric pressure in 24 hours. Basically, bombogenesis is the rapid intensification of a mid-latitude cyclone in a small period of time. When this happens, it can cause the storms that form along the cold front to become increasingly more intense than before, such as raging snow storms in the Northeast, as well as severe thunderstorms on a strong squall line (line of rapidly moving storms along a cold front that result in damaging winds, tornadoes, and heavy rain) to form along the front in the South. These can cause embedded tornadoes within the line itself, which is particularly more dangerous as these types of tornadoes are more likely to be rain-wrapped (where the rain will form a wall around the tornado causing it to be hidden and undetected without radar). 

Bombogenesis does not happen that frequently during the year, but when it does, it can get dangerous quick for the population that lies ahead of intense cyclone. More often than not, these systems typically become Nor’easters, and cause several inches to even feet of snow to fall over portions of the Northeast over a period of days as it pushes through. On the meteorological aspect of it, bombogenesis is a phenomenon that is exciting to see, but nerve wracking to forecast as some models struggle to agree on timing and severity. As instruments and models advance, these will be better forecasted in the future. 

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©2020 Meteorologist Ashley Lennard